Ambulatory low volume infusion pumps are known for use in connection with infusion of various fluids to a patient. In one prior art ambulatory battery-operated infusion device, a physician calibrates for a flow rate by adjusting a trimming potentiometer and viewing the adjustment on a meter. Various inaccuracies have been found using this prior art system.
In order to have a successful ambulatory infusion pump, it is essential that the pump have predictable variable speeds in order to give predictable flow rates. The selected flow rates must remain constant over various states of charge of the battery. Further, a reasonable torque control is required in order to be able to control the flow rates over the different speed settings.
It is, therefore, an object of the invention to provide a voltage regulator circuit that is operative with a battery-operated motor to provide predictable accurate flow rates (motor speeds) notwithstanding variable loads and notwithstanding the variable input voltages resulting from variations in the condition of the battery voltage.
It is another object of the present invention to provide a voltage regulator circuit which is constructed to have a terminal which can be connected to a computer or the like to measure the functioning of the circuitry, including the actual flow rates at all the speeds, the battery voltage and the current used.
A further object of the present invention is to provide a voltage regulator circuit that can be enclosed in a small module and be completely testable with a single output.
Other objects and advantages of the present invention will become apparent as the description proceeds.